Mammals rely on the metabolic functions of their gut microbiota to meet their energetic needs and digest potentially toxic components in their diet. The gut microbiome plastically responds to shifts in host diet and may buffer variation in energy and nutrient availability. However, it is unclear how seasonal differences in the gut microbiome influence microbial metabolism and nutrients available to hosts. In this study, we examine seasonal variation in the gut metabolome of black howler monkeys (
- PAR ID:
- 10217934
- Date Published:
- Journal Name:
- Microbiome
- Volume:
- 9
- Issue:
- 1
- ISSN:
- 2049-2618
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Alouatta pigra ) to determine whether those variations are associated with differences in gut microbiome composition and nutrient intake, and if plasticity in the gut microbiome buffers shortfalls in energy or nutrient intake. We integrated data on the metabolome of 81 faecal samples from 16 individuals collected across three distinct seasons with gut microbiome, nutrient intake and plant metabolite consumption data from the same period. Faecal metabolite profiles differed significantly between seasons and were strongly associated with changes in plant metabolite consumption. However, microbial community composition and faecal metabolite composition were not strongly associated. Additionally, the connectivity and stability of faecal metabolome networks varied seasonally, with network connectivity being highest during the dry, fruit‐dominated season when black howler monkey diets were calorically and nutritionally constrained. Network stability was highest during the dry, leaf‐dominated season when most nutrients were being consumed at intermediate rates. Our results suggest that the gut microbiome buffers seasonal variation in dietary intake, and that the buffering effect is most limited when host diet becomes calorically or nutritionally restricted. -
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Life history and socioecological factors have been linked to species‐specific patterns of growth across female vertebrates. For example, greater maternal investment in offspring has been associated with more discrete periods of growth and reproduction. However, in primates it has been difficult to test such hypotheses because very few studies have obtained growth measurements from wild populations. Here we utilize a promising noninvasive photogrammetric method—parallel lasers—to examine shoulder‐rump (SR) growth in a wild primate, the gelada (
Theropithecus gelada , Simien Mountains National Park, Ethiopia). In this species, a graminivorous diet coupled with high extrinsic infant mortality risk suggests that maternal investment in neonates is low. Therefore, in contrast with other closely related papionins, we expected female geladas to exhibit less discrete periods of growth and reproduction. For both sexes, we compared size‐for‐age patterns (N = 154 females;N = 110 males) and changes in growth velocity relative to major life history milestones. Female geladas finished 88.5% of SR growth by first sexual swelling, and 97.2% by first reproduction, reaching adult body size by 7.72 years of age. Compared to closely related papionins, gelada females finished more growth by first reproduction, despite producing relatively small, and presumably “cheap,” neonates. Male geladas finished 85.4% of growth at dispersal, and 96.0% at estimated first birth. Contrary to other polygynous primates, males are larger than females because they grow for a longer period of time (not because they grow faster), surpassing females around 6 years of age when female growth slows. Our results demonstrate that parallel lasers are an easy and promising new method that can be used to construct comprehensive life history perspectives that were once out of reach for wild populations. Am. J. Primatol. 78:707–719, 2016. © 2016 Wiley Periodicals, Inc. -
Although generally presumed to be isocaloric, dietary fats can differ in their energetic contributions and metabolic effects. Here, we show how an explicit consideration of the gut microbiome and its interactions with human physiology can enrich our understanding of dietary fat metabolism. We outline how variable human metabolic responses to different dietary fats, such as altered ileal digestibility or bile acid production, have downstream effects on the gut microbiome that differentially promote energy gain and inflammation. By incorporating host-microbial interactions into energetic models of human nutrition, we can achieve greater insight into the underlying mechanisms of diet-driven metabolic disease.more » « less
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Abstract Female social relationships are often shaped by the distribution of dietary resources. Socioecological models predict that females should form strict linear dominance hierarchies when resources are clumped and exhibit more egalitarian social structures when resources are evenly distributed. While many frugivores and omnivores indeed exhibit dominance hierarchies accompanied by differential resource access, many folivores deviate from the expected pattern and display dominance hierarchies despite evenly distributed resources. Among these outliers, geladas (Theropithecus gelada) present a conspicuous puzzle; females exhibit aggressive competition and strict dominance hierarchies despite feeding primarily on non-monopolizable grasses. However, these grasses become scarce in the dry season and geladas supplement their diet with underground storage organs that require relatively extensive energy to extract. We tested whether female dominance hierarchies provide differential access to underground storage organs by assessing how rank, season, and feeding context affect aggression in geladas under long-term study in the Simien Mountains National Park, Ethiopia. We found that the likelihood of receiving aggression was highest when feeding belowground and that the inverse relationship between rank and aggression was the most extreme while feeding belowground in the dry season. These results suggest that aggression in geladas revolves around belowground foods, which may mean that underground storage organs are an energetically central dietary component (despite being consumed less frequently than grasses), or that even “fallback” foods can influence feeding competition and social relationships. Further work should assess whether aggression in this context is directly associated with high-ranking usurpation of belowground foods from lower-ranking females following extraction.
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Abstract Male reproductive competition can select for condition‐dependent, conspicuous traits that signal some aspect of fighting ability and facilitate assessment of potential rivals. However, the underlying mechanisms that link the signal to a male's current condition are difficult to investigate in wild populations, often requiring invasive experimental manipulation. Here, we use digital photographs and chest skin samples to investigate the mechanisms of a visual signal used in male competition in a wild primate, the red chest patch in geladas (
Theropithecus gelada ). We analysed photographs collected during natural (n = 144) and anaesthetized conditions (n = 38) to understand variability in male and female chest redness, and we used chest skin biopsies (n = 38) to explore sex differences in gene expression. Male and female geladas showed similar average redness, but males exhibited a wider within‐individual range in redness under natural conditions. These sex differences were also reflected at the molecular level, with 10.5% of genes exhibiting significant sex differences in expression. Subadult males exhibited intermediate gene expression patterns between adult males and females, pointing to mechanisms underlying the development of the red chest patch. We found that genes more highly expressed in males were associated with blood vessel development and maintenance but not with androgen or oestrogen activity. Together, our results suggest male gelada redness variability is driven by increased blood vessel branching in the chest skin, providing a potential link between male chest redness and current condition as increased blood circulation to exposed skin could lead to heat loss in the cold, high‐altitude environment of geladas.
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1186/s40168-020-00977-9
